You have to have the foundation be strong before your try to build more and more levels on top of it. Mitsu needs to sell cars under their own name and be succesfull before they can persuade buyers to pay "more" for dressed up Mitsus under another name. "Saabaru" as you call it, is over. GM has dumped their shares of Subaru and Toyota picked up most of them, so there won't be any more "Saabarus" And how that JV had any parrallels to do with Toyota/Lexus, Acura/Honda, or Nissan/Infiniti would take an extreme stretch of the imagination. No one ever marketed a Saab as a step for Subaru owners who wanted more.

If anything Mitsu and Hyundai have/had this relationship as Hyundai through the 80's and 90's had been using older Mitsu platforms and engines to sell cars, now they've found their niche in the market and have a stronger footing here then Mitsu does. Now its Mitsus turn to decide if they want to be an everyman appliance dealer like Toyota, or build niche products, or build premium imports somwhere below Lexus, but above the typical Toyota. My guess is they'll try to establish a brand DNA more exciting then the typical Honda or Toyota, but still compete at that level - but offer more and more Evoish/Ralliart style gear for the enthusiasts.

A lux division would be a foolish endeavor IMO. It takes millions of dollars to establish before a single car is built and you aren't going to get weary/wary dealers to spend the money to open/build them considering how much a Mitsu franchise is worth these days.